Integrating Anthropic Claude

Install

pip install verdifax anthropic

Two-call pattern

The simplest pattern: call Claude, then attest the result.

import anthropic
import verdifax

claude = anthropic.Anthropic()  # picks up ANTHROPIC_API_KEY

resp = claude.messages.create(
    model="claude-sonnet-4-6",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Summarize this document..."}],
)
output = resp.content[0].text

receipt = verdifax.attest_claude_response(
    prompt="Summarize this document...",
    response=output,
    program_id="a" * 64,            # your registered program id
    route_id="claude-summarize-v1",
    registry_record_hash="b" * 64,  # your registry record hash
)

print(f"Claude said: {output}")
print(f"Verdifax seal: {receipt.manifest_hash}")

receipt.manifest_hash is the artifact you keep. Same prompt + same response = same hash, every time.

Payload canonicalization: helper-specific prefix

Important: The Claude helper uses a helper-specific canonicalization format. This is NOT the canonical format for raw verdifax.attest() calls.

Inside the helper, Verdifax canonicalizes the prompt + response with a Claude-specific prefix:

verdifax.helper.claude.v1
verdifax.helper.prompt.v1
<prompt>
verdifax.helper.response.v1
<response>

Example: If you call:

verdifax.attest_claude_response(
    prompt="What is 2+2?",
    response="4",
    ...
)

The bytes hashed by the orchestrator are:

verdifax.helper.claude.v1
verdifax.helper.prompt.v1
What is 2+2?
verdifax.helper.response.v1
4

This means an identical prompt + response pair sent through attest_openai_response() produces a different manifest hash than through attest_claude_response(). That's intentional, the same text under different providers is meaningfully different evidence.

Without the helper

If you want to attest Claude calls without the helper's prefix, build the payload yourself:

payload = f"prompt:{prompt}\nresponse:{response}"
receipt = verdifax.attest(
    payload=payload,
    program_id="...",
    ...
)

This will hash the raw payload without any provider-specific prefix. You lose the provider separation but gain full control over what bytes are sealed.

Reusing a connection pool

For high-throughput servers, share one VerdifaxClient:

from verdifax import VerdifaxClient
import anthropic

claude = anthropic.Anthropic()
verdifax_client = VerdifaxClient()

def attest_one(prompt: str) -> str:
    resp = claude.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
        messages=[{"role": "user", "content": prompt}],
    )
    output = resp.content[0].text
    receipt = verdifax.attest_claude_response(
        prompt=prompt,
        response=output,
        program_id="a" * 64,
        route_id="claude-summarize-v1",
        registry_record_hash="b" * 64,
        client=verdifax_client,
    )
    return receipt.manifest_hash

Async (FastAPI / async workers)

from verdifax import AsyncVerdifaxClient
import anthropic

claude = anthropic.AsyncAnthropic()

async def attest_async(prompt: str):
    resp = await claude.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
        messages=[{"role": "user", "content": prompt}],
    )
    output = resp.content[0].text
    async with AsyncVerdifaxClient() as v:
        receipt = await v.attest(
            payload=f"prompt:{prompt}\nresponse:{output}",
            program_id="a" * 64,
            route_id="claude-summarize-v1",
            registry_record_hash="b" * 64,
        )
        return receipt.manifest_hash

What gets sealed

The helper sends Verdifax exactly two pieces of data: the prompt text and the response text. It does not send your Anthropic API key, conversation metadata, or system prompts. If you need those sealed too, build the payload yourself and call verdifax.attest() directly.

Continue

• Integrating OpenAI
• Integrating LangChain
• Python SDK, attest()